Hollow drill sharpener



April 22, 1969 B, F DIRZIUS 3,439,565

HOLLOW' DRILL SHARPENER Filed Oct. e, 1966 United States Patent O Claim ABSTRACT F THE DISCLOSURE My hollow drill Sharpener has a hollow hand sized body member to receive a pair of cylindrical bushings spaced by a central hollow fastening ring supporting a cutting member extending into each of said bushings with a single flute cutting edge on each end extending into but vnot contacting said bushing. -Each of said bushings is adapted to receive a hollow drill inserted up to the cutting edge, without obstruction, to be sharpened by rotation against the cutting edge, the hollow drill being supported by the bushing immediately back of the cutting edge during sharpening to prevent formation of burrs or ragged edges on the hollow drill.

My invention relates to a metal Sharpener for a metal drill in the form of a hollow tube with an open top. Such drills used for cutting holes in paper have top edges that frequently must be sharpened.

Heretofore, Sharpeners for such hollow tube drills created rough top edges with burrs. It was then necessary to go through a second operation to remove these rough edges and burrs by honing. This often resulted in uneven edges, increased wear, breakage, and replacement with delay and added cost.

It is among the objects of my invention to solve these problems and remove these objectionable characteristics; to provide a hollow drill Sharpener assembly having bushings and a smaller ring within a body member for holding and supporting a cutting member during the sharpening of a hollow drill, so that the cutting member is supported by a bushing immediately back of the cutting member so as to prevent the metal from bending over and forming burrs thereby eliminating a later secondary honing operation to remove the burrs; to suppy a Sharpener that will insure razor sharp cutting edges free of roughness; and to provide a structure that will provide free rotation of the drill Without obstruction during the sharpening operation.

My invention contemplates such other objects, advantages and capabilities as will later more fully appear and which are inherently possessed by my invention.

While I have shown in the accompanying drawings a preferred form of my invention, yet it is to be understood that the same is susceptible of modification and change without departing from the spirit of my invention.

Referring to the drawings, FIG. l is a top plan view of my hollow drill Sharpener; FIG. 2 is an elevational view of the hollow drill to be sharpened; FIG. 3 is a sectional view on line 3 3 of FIG. 1; FIG. 4 is a longitudinal sectional view on line 4 4 of FIG. 1; LFIG. 5 is an enlarged end view of my Sharpener; FIG. 6 is a sectional view on line `6-6 of FIG. 5; FIG. 7 is a perspective view of my body member; FIG. 8 is a perspective group view of my bushings, ring and cutting member; and FIG. 9 is a perspective view of my cutting member.

The embodiment selected to illustrate my invention comprises a body member 10I having a cylindrical bore 11 extending laterally therethrough. Within bore 11 are a pair of removable spaced identical cylindrical hardened steel bushings 12, and a smaller removable cylindrical assembly locking ring |13 placed therebetween. Said ring l13- ice has a smaller outer diameter than the diameter of each of bushings .12.

Each of bushings 12 has a cylindrical bore `14 extending laterally therethrough communicating with a cylindrical bore 15 of the same diameter in ring 13.

A cutting member 116 has a rounded portion 17 corresponding to the cylindrical surfaces of bores 14 and 1'5. At each end cutting member I16 has a single flute cutting edge 18, preferably at an included angle of 82. This included angle may vary between 68 and 89. Each cutting edge is radially relieved.

Cutting member 16 extends within bore 15 of ring 13 and beyond it into bore .14 of bushing -12 on either side.

Body member =10 has a screw threaded opening 19 extending through to bore i11 to receive screw 20. When screw 20 is tightened against ring 13, the ring presses rounded portion 17 of cutting member 16 against the inner surface of bore 14 of bushing 12 adjacent the cutting edge 1-8.

When screw 20L is tightened against ring :13 the cutting member 1-6 holds bushing 12 in xed position.

In use the end of the hollow drill 21, to be sharpened, is inserted into bore 14 of either bushing 12 up to the cutting edge .18 of cutting member 16, and freely rotated without obstruction until the sharpening of the drill has been completed.

The hollow drill 2\1 being sharpened is supported in bore 14 of bushing '12 right back of the cutting edge y18 of cutting member 16 so as to prevent the bending over of the metal on the hollow drill and the forming of burrs. This insures the sharpening of a ra-zor like edge on the hollow drill. There are no burrs or ragged edges to be removed by honing and no delays due to breakage and replacement.

My hollow drill Sharpener is extremely simple and uncomplicated in construction, economical to make, light in weight, hand sized and manually operable, and extremely portable for use anywhere, and efcient in operation with elimination of burring and waste in the d rills sharpened.

Having thus described my invention, I claim:

1. A portable hollow drill Sharpener comprising a hand sized body member having a cylindrical bore extending laterally therethrough a pair of spaced cylindrical bushings removably positioned in the bore 'of said body member, a cylindrical assembly locking ring removably positioned within the bore of said body member and between said spaced bushings, said ring having a smaller outer diameter than the diameter of each of said spaced bushings, said spaced bushings and said ring each having a cylindrical bore of the same diameter extending laterally therethrough with the bores of the bushings in communication with the bore of the ring, a cutting member having a central rounded portion corresponding to the cylindrical bores of said bushings and said ring, said cutting member positioned within said ring and extending into the bores of said spaced bushings, said body member having a screw threaded opening extending longitudinally from its exterior to its bore, and a screw extending into the screw threaded opening and upon being tightened to contact said ring and to press said central rounded portion of said cutting member against said bushings to hold said cutting member in xed position, said cutting member having at each end a single ute cutting edge within the bores of said spaced bushings and Without contact with said bushings, so that when a hollow drill inserted into the bore of either of said bushings and supported by said bushing, is pressed against the cutting edge of said cutting member and rotated thereagainst the drill is sharpened, said cutting edge not being ncked by contact with said bushings, and the inserted hollow drill being supported by the bushing immediately back of said cut- 3 4 ting edge during sharpening to prevent the formation of 2,141,712 12/ 1938 Gylleck 76-82 burrs or ragged edges on the hollow drill. 3,068,720 12/ 1962 Dirzius 76-82 References Cited THERON E. CONDON, Primary Examiner.

UNITED STATES PATENTS 5 U.S. Cl. X.R.

2,125,566 8/1938 Hill 76-82 77-73 

